Magnetically-retained shielding cap for peristaltic pump

ABSTRACT

A shielding cap with a cover for use with a peristaltic pump includes a magnet to generate an attractive force between the shielding cap and a pump component to retain the shielding cap in place, and may further include a lip which allows the shielding cap to rest flush against a pump component, and a sidewall which allows the shielding cap to seal an opening in a pump component.

CROSS REFERENCE TO RELATED APPLICATIONS

Not Applicable.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

Not Applicable.

BACKGROUND

The present invention relates in general to a shielding cap and, more specifically, to a magnetically-retained shielding cap for a peristaltic pump.

A peristaltic pump is a mechanical device that uses contraction of a flexible tube to propel fluid through the tube as the contraction is translated along the tube length by the pump. An exemplary peristaltic pump includes a housing defining a curved surface. A flexible tube for fluid communications is installed in the pump along the curved surface of the pump housing. A rotatable assembly is centrally located in the pump housing and includes a roller that engages the tube to progressively compress it against the curved surface of the pump housing as the roller moves in a curved path along housing with the rotation of the rotatable assembly. The pump housing and flexible tube are held stationary so that when the rotatable assembly is rotated relative to the pump housing, the point of tube compression propels the fluid in the tube from a fluid source at one end through and along the length of the tube.

A peristaltic pump can be used during cardiovascular surgery to facilitate circulation of blood between a patient and a heart-lung machine. Peristaltic pumps can generate a constant fluid flow rate and employ disposable tubes, making their use beneficial in medical applications.

Multiple rollers are typically provided in an exemplary peristaltic pump for compression at multiple points along the curved surface of the pump housing to maintain a constant fluid flow rate as the rollers move into and out of engagement with the tube. To accommodate multiple tube sizes and wall thicknesses, the exemplary peristaltic pump can also include a mechanism that allows adjustment of the distance between the rollers and the curved surface of the housing.

The rotatable assembly in a peristaltic pump is typically driven by a drive mechanism including an electric motor connected to a drive shaft to move the rotatable assembly. The operation of the electric motor may be controlled by a computer control system which enables modulation of motor speed to generate the desired fluid flow rate.

A typical peristaltic pump designed for medical applications will also include a feature to enable the manual operation in order to generate fluid flow in the event of a power failure or malfunction of the computer control system. This feature may include an aperture for the mechanical engagement of a hand crank allowing an operator to manually impart rotational motion to the drive shaft of the peristaltic pump. In order to protect against debris or fluid ingress to the pump mechanisms, particularly during storage or cleaning, a typical peristaltic pump includes a cap to isolate the manual operation feature from the environment.

Conventional caps have used, for example, a force fit where tabs extend from the cap into the interior of the pump to retain the cap to the pump. These tabs may deflect during installation and removal of the cap. Accordingly, there is a need for an improved shielding cap that prevents debris or fluid ingress to the internal pump mechanisms and that can be removed with ease.

SUMMARY OF THE INVENTION

In one embodiment of the present disclosure, a shielding cap includes a cover, and a magnet supported on the cover. The shielding cap can further include a lip that allows the shielding cap to sit flush against a supporting component of the peristaltic pump. The shielding cap can further include a sidewall that aligns the shielding cap when installed on a pump mechanism and blocks any ingress path for fluid or debris into the pump mechanism. The magnet may be overmolded in the material of shielding cap. The magnet may alternatively be retained to the cap by an adhesive or clips. The magnet is provided in the shielding cap to generate an attractive force between the shielding cap and a pump component to retain the cap in place during use, while remaining easily removable.

In another embodiment of the present disclosure, a peristaltic pumping assembly includes a peristaltic pump having a component with an opening, where a shielding cap engages the component at the opening. The shielding cap includes a cover and a magnet supported on the cover. The pumping assembly can include a shaft and the cap may be retained to the pumping assembly through magnetic attraction to the shaft, and is spaced apart from the shaft. The pump component may be an adjustment knob, and the shielding cap can include a lip supported on the cover of the cap to engage the adjustment knob. The shielding cap can also include a sidewall supported on the cover to extend into the adjustment knob. The shaft of the pumping assembly can also include an engagement feature for manual operation of the peristaltic pump.

In a further embodiment of the present disclosure, a peristaltic pump includes a pump housing that has a curved surface. A drive mechanism is supported on the pump housing and a rotatable assembly is in mechanical engagement with the drive mechanism. The rotatable assembly includes a shaft drivable by the drive mechanism, one or more rollers, and an adjustment knob capable of changing a separation distance between rollers and the shaft. The peristaltic pump also includes a shielding cap in contact with the adjustment knob, where the shielding cap includes a cover, and a magnet supported on the cover. The shielding cap can also include a lip supported on the cover and a sidewall supported on the cover that extends into the adjustment knob. The shaft can include an engagement feature for manual rotation of the rotatable assembly and the shielding cap can be magnetically retained to the shaft at the engagement feature for manual rotation of the rotatable assembly, and is spaced apart from the shaft.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a rotatable assembly for a peristaltic pump including a shielding cap.

FIG. 2 is a top plan view of a peristaltic pump including a shielding cap.

FIG. 3 is a partial cross-sectional view of a shielding cap installed on a rotatable assembly for a peristaltic pump.

FIG. 4 is a cross-sectional view of an alternative shielding cap.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to FIG. 1, a perspective view of an exemplary rotatable assembly for a peristaltic pump is shown. The rotatable assembly includes a rotatable body 30 that supports the components comprising the rotatable assembly. Rollers 35 are mounted in roller slides 32 supported in the rotatable body 30. The roller slides 32 are mounted on a cam block (not shown) within the rotatable body 30 that allows the roller slides 32 to be adjusted inwardly and outwardly from the rotatable body 30. An adjustment knob 20 is provided on the rotatable body 30 to allow an operator to perform the adjustment of the roller slides 32. A drive shaft 40 extends through the center of the rotatable body 30. The lower end of the drive shaft 40 can interface with a drive mechanism 45 including, for example, an electric motor and control system, to rotate the rotatable body 30 in the peristaltic pump. The upper end of the drive shaft 40 extends upward through the rotatable body 30 and into the adjustment knob 20. A shielding cap 10, according to the present disclosure, is provided on the adjustment knob 20.

Referring now to FIG. 2, the exemplary rotatable assembly is shown within a pump housing 50 and with a flexible tube 60. The flexible tube 60 is compressed against the curved surface of the pump housing 50 by the rollers 35. Roller guides 37 may be mounted to the rotating body 30 above and below the flexible tube 60 on both sides of the rollers 35 to retain the flexible tube 60 at a proper orientation within the pump housing 50 to engage with the rollers 35. The rotatable assembly rotates in operation to translate points of compression along the length of the flexible tube 60 to generate fluid flow as the flexible tube 60 and the pump housing 50 are held rigidly in place, for example, by tube clamps (not shown) and a pump base (not shown). The adjustment knob 20 may be turned relative to the rotatable body 30 to increase or decrease the separation distance between the rollers 35 and the drive shaft 40 and thereby increase or decrease the amount of compression of the flexible tube 60 installed in the peristaltic pump.

Referring now to FIG. 3, the shielding cap 10 is shown installed on the adjustment knob 20. Enclosed within the adjustment knob 20 is the upper end of the drive shaft 40, which extends through the rotatable body 30. In the illustrated embodiment, the upper end of the drive shaft 40 terminates below the top edge of the adjustment knob 20. The upper end of the drive shaft 40 may include engagement features for manual operation of the rotatable assembly. In the illustrated embodiment, the upper end of the drive shaft 40 is a cylindrical pocket that includes pin 42. Pin 42 allows a forked hand crank (not shown) to be inserted into the upper end of the drive shaft 40 to manually rotate the rotatable body 30 in the event of a failure or malfunction of the drive mechanism 45. In alternative embodiments, the drive shaft 40 may have, for example, a square pocket, an elongated slot, or any other suitable configuration to engage with an alternative source of rotational force, including a hand crank or other equivalent mechanisms known in the art. In further alternative embodiments, the drive shaft 40 may include an engagement feature for manual operation at a lower end along with a drive mechanism interface at an upper end. Other embodiments may include both the engagement feature for manual operation and the drive mechanism interface at the same end, either lower or upper, of the drive shaft 40.

The shielding cap 10 is preferably formed of plastic, polymeric, or resin material. The material may be chosen according to its manufacturability, dimensional stability, and suitability for exposure to chemicals, for example, cleaning chemicals, found in a medical or other application. The shielding cap 10 may be formed by an injection molding process or other suitable manufacturing process. In the illustrated embodiment, the adjustment knob 20, the rollers 35, and roller slides 32 are formed of aluminum, and the drive shaft 40 is formed of steel using conventional means known in the art. However, alternative embodiments may include an adjustment knob 20, rollers 35, roller slides 32, and drive shaft 40 formed of any other suitable material.

The shielding cap 10 is shaped to correspond to the opening provided for access to the manual operation engagement feature of the drive shaft 40. In the illustrated embodiment, the opening is provided in the adjustment knob 20 as a circular hole. Thus, the shielding cap 10 is circular in shape and is of a sufficient size to cover the entire opening formed through the top of the adjustment knob 20. The shielding cap 10 includes a cover 105 that extends over the opening of the adjustment knob 20, as best illustrated in FIG. 3. In certain alternative embodiments, the opening provided for accessing the drive shaft 40 may be rectangular or another shape, and the shielding cap 10 for that application would be correspondingly shaped to fully cover that rectangular or other shaped opening. In the illustrated embodiment, the cover 105 forms a convex curved surface on the top of the shielding cap 10. In alternative embodiments, the cover 105 may be flat, concave, or have another profile.

The shielding cap 10 further includes a lip 110. In the illustrated embodiment, the lip 110 is a continuous, flat annulus disposed peripherally adjacent to the cover 105. The lip 110 is of complementary size and shape to the upper surface or edge of the adjustment knob 20 to allow the shielding cap 10 to rest flush against the adjustment knob 20 to form a fluid and debris barrier. In alternative embodiments, for example, a rectangular shielding cap may include a rectangular lip. In a further alternative embodiment, a rectangular shielding cap may include an annular peripheral lip, and a circular shielding cap may include a rectangular lip depending on the shape of the opening provide for accessing the drive shaft 40. Additionally, the cover 105 of the shielding cap 10 may extend beyond the lip 110 so that the lip 110 is not at the outermost periphery of the cap 10.

The shielding cap 10 also includes a sidewall 115. In the illustrated embodiment, the sidewall 115 extends from the lip 110 of the shielding cap 10 opposite the cover 105 and within the opening of the adjustment knob 20 as shown in FIG. 3. The sidewall 115 helps retain the shielding cap 10 centered in the opening of the adjustment knob 20. The shielding cap 10 is illustrated with the sidewall 115 adjacent to the lip 110. In alternative embodiments, the sidewall 115 may be spaced apart from the lip 110. The sidewall 105 is preferably shaped and sized according to abut an edge of the opening in which the shielding cap 10 is installed. The shielding cap 10 is illustrated with a continuous sidewall 105. In alternative embodiments, the sidewall 105 may be discontinuous, segmented, or extend about partial or select portions of the shielding cap 10.

The shielding cap 10 is shown in FIG. 3 with a sidewall cross-section having squared edges. In the alternative embodiment illustrated in FIG. 4, the shielding cap 10′ includes a sidewall 115′ having a tapered cross-section. The circumference of that portion of the sidewall 115′ adjacent to the peripheral lip 110′ is sized to approach the circumference of the opening of the adjustment knob 20. As the sidewall 115′ extends away from the peripheral lip 110′, the sidewall tapers away from the peripheral lip 110′. This feature may increase the ease by which the shielding cap 10′ is installed into the opening of the adjustment knob 20 as compared with shielding cap 10. In further alternative embodiments, the sidewall 115 may have other cross-sectional shapes, including rounded, angled, or any other suitable shape.

As shown in FIG. 3, the shielding cap 10 includes a magnet 120 opposite the cover 105 and centered on the shielding cap 10. The magnet 120 may be over-molded into the material of the shielding cap 10, for example, through an injection molding process. Alternatively, the magnet 120 may be attached or affixed to the shielding cap 10 through adhesives or other mechanical retention mechanisms. For example, in the alternative embodiment of the shielding cap 10′ illustrated in FIG. 4, the magnet 120 is retained on the shielding cap 10′ with press-in retaining clips 122 and an adhesive 125 disposed between the magnet 120 and the cover 105′. Although the clips 122 and adhesive 125 are illustrated in combination, they may be used separately in further alternative embodiments. The shielding cap 10 is illustrated with the sidewall 115 encircling the magnet 120. In alternative embodiments the magnet 120 may not be encircled by sidewall 115, including for example, where the magnet extends into or across the sidewall or where the sidewall 115 is discontinuous, partial or otherwise not circular.

As best shown in FIG. 3, the shielding cap 10 is placed atop the adjustment knob 20 so that the peripheral lip 110 of the shielding cap 10 rests flush against the top surface of the adjustment knob 20. The shielding cap 10 is aligned and centered on the adjustment knob 20 by the sidewall 115. The shielding cap 10 is held in place through the magnetic attraction between the magnet 120 and the drive shaft 40. The height of the shielding cap 10 and magnet 120 are selected so that the magnet is close to the drive shaft 40 but spaced apart, separated by a gap 47. The gap 47 may include a separation between the cap 10 and the shaft 40 of an air gap of about 0.020″. Alternatively, the gap 47 may include an air gap larger than about 0.020″, or smaller than about 0.020″, such that the magnet 120 is in magnetic attraction to the shaft 40 while the shaft 40 remains unimpeded by the cap 10 in operation. The size and the strength of the magnet 120 and the size of the gap 47 are selected so that the attractive magnetic force is sufficient to operate across the gap 47 to hold the cap 10 without contacting any moving parts, including the draft shaft 40, during pump operation. This configuration imparts sufficient attraction between the shielding cap 10 and the drive shaft 40 so that the shielding cap 10 is retained securely in place against dislodgement during storage, transportation, and normal operation of the peristaltic pump. Further, the cap remains easily removable for manual operation of the pump and eliminates any force fit of the conventional design involving tabs extending from the cap.

In the illustrated embodiment, the adjustment knob 20 is formed of a non-magnetic material, such as aluminum, while the drive shaft 40 is formed of a magnetic material, such as steel. In this configuration, the magnetic attraction is between the magnet 120 of the shielding cap 10 and the drive shaft 40. Alternative configurations may include different material selections where, for example, the adjustment knob 20 is formed of a magnetic material, and the drive shaft 40 is formed of a non-magnetic material. In such a configuration, the shielding cap 10 may be retained in place through the attractive force between the shielding cap 10 and the adjustment knob 20.

While the above disclosed shielding cap has been illustrated with respect to a particular application in a rotary peristaltic pump's adjustment knob, it should be apparent to one skilled in the art that the applications of the shielding cap extend to other configurations of peristaltic pumps. This may include, for example, a peristaltic pump where access to a drive shaft is not provided through an adjustment knob. Additionally, it should be apparent to one skilled in the art that the application of the disclosed shielding cap extends beyond rotary peristaltic pump to other pump types and configurations. For example, an alternative peristaltic pump type may include a series of compression plates on a drive shaft including cams that rotate with the drive shaft to move the compression plates sequentially toward and away from a flat plate. The movement of the compression plates can progressively compresses a flexible tube against the flat plate to generate fluid flow in the tube in a rectilinear path along the flat plate. In this alternative peristaltic pump, a pump housing may enclose the drive shaft and include an aperture through which an end of the drive shaft is similarly accessible for manual drive operation. The shielding cap of the present disclosure may be used in this application to similarly seal against the pump housing to prevent fluid and debris ingress into the pump housing through the aperture. 

What is claimed is:
 1. A shielding cap comprising: a cover, a lip supported on the cover for engaging a peristaltic pump, a sidewall supported on the cover for extending into the peristaltic pump, and a magnet supported on the cover for magnetic retention of the shielding cap to the peristaltic pump.
 2. The shielding cap of claim 1, wherein the cover includes an outer edge and wherein the lip is a peripheral lip adjacent to the outer edge of the cover.
 3. The shielding cap of claim 1, wherein the sidewall is adjacent to the lip.
 4. The shielding cap of claim 1, wherein the magnet is encircled by the sidewall.
 5. The shielding cap of claim 1, wherein the lip and the sidewall are integral with the cover.
 6. The shielding cap of claim 1, wherein the sidewall extends continuously about the cover adjacent to the lip.
 7. The shielding cap of claim 1, wherein the sidewall extends discontinuously about the cover adjacent to the lip.
 8. The shielding cap of claim 1, wherein the sidewall has a tapered cross-section.
 9. The shielding cap of claim 1, wherein the magnet is overmolded to the cover.
 10. The shielding cap of claim 1, wherein the magnet is retained to the cover by one of an adhesive, clips, and a combination of adhesive and clips.
 11. A peristaltic pumping assembly comprising: a peristaltic pump having a component, the component including an opening, and a shielding cap engaging the component at the opening, the cap including a cover and a magnet supported on the cover.
 12. The peristaltic pumping assembly of claim 11, wherein the peristaltic pump further includes a shaft, and wherein the cap is retained on the component through magnetic attraction to the shaft.
 13. The peristaltic pumping assembly of claim 11, wherein the component includes an adjustment knob, and wherein the shielding cap includes a lip supported on the cover, the lip engaging the component.
 14. The peristaltic pumping assembly of claim 11, wherein the component includes an adjustment knob, and wherein the shielding cap further includes a sidewall supported on the cover, the sidewall extending into the peristaltic pump at the adjustment knob.
 15. The peristaltic pumping assembly of claim 12, wherein the shaft includes an engagement feature for manual operation of the peristaltic pump and wherein the shielding cap is in magnetically retained to the shaft at the engagement feature for manual operation of the peristaltic pump.
 16. The peristaltic pumping assembly of claim 15, wherein the shielding cap is spaced apart from the shaft.
 17. A peristaltic pump comprising: a pump housing including a curved surface, a drive mechanism supported on the pump housing, a rotatable assembly in mechanical engagement with the drive mechanism, the rotatable assembly including a shaft drivable by the drive mechanism, a plurality of rollers, and an adjustment knob capable of changing a separation distance between the plurality of rollers and the shaft, and a shielding cap disposed in contact with the adjustment knob, the shielding cap including a cover, and a magnet supported on the cover.
 18. The peristaltic pump of claim 17, wherein the shielding cap further includes one of a lip supported on the cover, a sidewall supported on the cover extending into the adjustment knob; and combination of a lip supported on the cover and a sidewall supported on the cover extending into the adjustment knob.
 19. The peristaltic pump of claim 17, wherein the shaft includes an engagement feature for manual rotation of the rotatable assembly, and wherein the shielding cap is magnetically retained to the shaft at the engagement feature for manual rotation of the rotatable assembly.
 20. The peristaltic pump of claim 17, wherein the shielding cap is spaced apart from the shaft. 